What tincture rules?

12the quarter: Gules, a lion rampant Sable guttee de l'armes [ ] ?

The 12th quarter of the arms of Brereton of Ashley, as recorded in the Visitations of Chester 1613, are an unusual but not unpleasant design. Unfortunately they are not identified and in fact marked as "doubtful" - probably because of the dreaded tincture rule (which is in fact more than once broken in "genuine" ancient Cheshire arms).